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Fatigue is a common phenomenon in airline pilots that can impair alertness and ability of crewmembers to safely operate an aircraft and perform safety related tasks. Fatigue can increase the risk of an incident or even an accident. This study provides the first prevalence values for clinically significant fatigue in Portuguese airline pilots. The hypothesis that medium/short-haul pilots may currently present different levels of fatigue than long-haul pilots was also tested. A survey was conducted by requesting Portuguese airline pilots to complete questionnaires placed in the pilots' personal lockers from 1 April until 15 May 2012. The questionnaire included the self-response Fatigue Severity Scale (FSS) to measure subjective fatigue and some additional questions concerning perception of fatigue by pilots. The prevalence values for total and mental fatigue achieved in the Portuguese airline pilots were: 89.3% (FSS > or = 4) and 94.1% (FSS > or = 4) when splitting the sample in two subsamples, long- and medium/short-haul pilots. Levels of total and mental fatigue were higher for medium/short-haul pilots. The analysis of fatigue levels in each type of aviator showed that medium/short-haul pilots presented the highest levels of total and mental fatigue. This study produced the first prevalence values of total and mental fatigue among Portuguese airline pilots, which represents a great step to understanding and addressing this critical phenomenon.
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RESEARCH ARTICLE
828 Aviation, Space, and Environmental Medicine x Vol. 84, No. 8 x August 2013
R EIS C, M ESTRE C, C ANHÃO H. Prevalence of fatigue in a group of
airline pilots. Aviat Space Environ Med 2013; 84:828 33.
Background: Fatigue is a common phenomenon in airline pilots that
can impair alertness and ability of crewmembers to safely operate an
aircraft and perform safety related tasks. Fatigue can increase the risk of
an incident or even an accident. This study provides the fi rst prevalence
values for clinically signifi cant fatigue in Portuguese airline pilots. The
hypothesis that medium/short-haul pilots may currently present different
levels of fatigue than long-haul pilots was also tested. Methods: A survey
was conducted by requesting Portuguese airline pilots to complete
questionnaires placed in the pilots personal lockers from 1 April until
15 May 2012. The questionnaire included the self-response Fatigue Se-
verity Scale (FSS) to measure subjective fatigue and some additional
questions concerning perception of fatigue by pilots. Results: The preva-
lence values for total and mental fatigue achieved in the Portuguese air-
line pilots were: 89.3% (FSS 4) and 94.1% (FSS 4) when splitting the
sample in two subsamples, long- and medium/short-haul pilots. Levels
of total and mental fatigue were higher for medium/short-haul pilots.
Discussion: The analysis of fatigue levels in each type of aviator showed
that medium/short-haul pilots presented the highest levels of total and
mental fatigue. This study produced the fi rst prevalence values of total
and mental fatigue among Portuguese airline pilots, which represents a
great step to understanding and addressing this critical phenomenon.
Keywords: aviation , fatigue , prevalence , pilots .
F
ATIGUE IS AN important factor in modern aviation,
usually attributed to long duty periods, disruptive
schedules, circadian disruptions, and sleep deprivation
( 3 ). There are several defi nitions of fatigue in the litera-
ture; however, this paper discusses fatigue in the context
of the commercial aviation industry. Fatigue is defi ned
by the International Civil Aviation Organization, the en-
tity responsible for supervising civil aviation, as a physi-
ological state of reduced mental or physical performance
capability resulting from sleep loss or extended wake-
fulness, circadian phase, or workload (mental and/or
physical activity) that can impair a crewmember s alert-
ness and ability to safely operate an aircraft or perform
safety related duties ( 12 ).
Over the last 30 yr, air traffi c around the world has
doubled every 10 yr. Total costs have also risen. Begin-
ning in the early eighties, the cost of fuel was the main
factor. But after the terrorist attacks of September 2001,
the costs associated with passenger security created
an additional expense ( 8 , 17 ). The “ low cost/low fares ”
model, which appeared in the late seventies, has also in-
creased airline competition to reduce fares. The combi-
nation of rising costs and reduced fares in the last 10 yr
has created an emphasis on effi ciency and productivity.
Reducing the costs of labor is a number one priority for
most companies and also translates to extended work/
y periods for aircrew. The maximum duty and mini-
mum rest present in fl ight and rest legislation are Goals
of Productivity for the majority of airlines around the
world ( 8 , 17 ). As such, it is not surprising that fatigue is a
clear and real risk among commercial airline pilots.
NASA s Aviation Safety Reporting System indicates that
21% of reported aviation events are fatigue related ( 24 ).
While general fatigue is important for any professional,
mental fatigue is extremely important in this profes-
sional group, taking into account all the demands of safe
airline fl ight. Mental fatigue refers to a feeling that can
be experienced during or after long periods of cognitive
activity. It involves fatigue, exhaustion, decreased level
of commitment to the task, and may even lead to a strong
will to stop performing ( 1 , 4 ). Pilot s fatigue is a genuine
concern in terms of safety, health, effi ciency, and pro-
ductivity ( 9 ), and the quantifi cation of this phenomenon
is of major importance to the pilots well-being and pas-
senger ’ s safety.
Aviator fatigue is common and well discussed by the
scientifi c community ( 5 , 20 , 25 ), noting that it decreases
performance and increases the risk for an incident or
even an accident ( 6 ). In a recent study of fatigue in United
Kingdom (UK) pilots, 71% of those who fl ew medium-
haul fl ights reported fatigue. More concerning were the
data that 81% of those reporting fatigue claimed that
their fatigue was worse than 2 yr prior ( 13 ). The sample
may not have been wholly representative of the pilots
population from the Professional Pilot s Rumours Net-
work ( www.pprune.com ) website, since it only covered
162 individuals from a population of 49,500 registered
pilots. Nevertheless, a high level of fatigue was reported
and an increase in the burden of fatigue was also sug-
gested ( 13 ). Similarly, in a study developed in a British
airline company, Houston et al. ( 10 ) refer in their work to
a fatigue reporting incidence value of 103 per 1000 pilots
per year.
There are two different types of fl ights: medium/
short-haul and long-haul fl ights. Medium/short-haul
operations are fl ights with less than 6 h duration with
several sectors in one duty period. Long haul operations
are fl ights with 6 or more hours, usually with one or two
From the Rheumatology Research Unit, Instituto de Medicina Molecu-
lar, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
This manuscript was received for review in September 2012. It
was accepted for publication in February 2013.
Address correspondence and reprint requests to: Cátia Reis, 11°A
1600-896 Lisboa, Av. Egas Moniz, Lisboa, Portugal; reis.catia@gmail.
com .
Reprint & Copyright © by the Aerospace Medical Association,
Alexandria, VA.
DOI: 10.3357/ASEM.3548.2013
Prevalence of Fatigue in a Group of Airline Pilots
Cátia Reis , Catarina Mestre , and Helena Canhão
Aviation, Space, and Environmental Medicine x Vol. 84, No. 8 x August 2013 829
FATIGUE IN AIRLINE PILOTS REIS ET AL.
sectors maximum. Due to their distinct characteristics,
the two types of fl ight operations may create different
levels of fatigue. Therefore, we hypothesized that me-
dium/short-haul pilots may currently present different
levels of fatigue from long-haul pilots, based on the fact
that these pilots have less total time in low phases of
ight than long-haul pilots ( 15 , 22 ). To test that hypoth-
esis, we used the 9-item Fatigue Severity Scale (FSS) ( 14 ),
one of the most commonly used self-report questionnaires
to measure fatigue. This work aimed to: 1) identify and
quantify the prevalence value of self-reported total and
mental fatigue in the community of Portuguese pilots;
and 2) assess and compare the level of fatigue in the two
most common types of fl ight: medium/short-haul and
long-haul.
METHODS
Study Population
From a questionnaire applied to a total population
of approximately 1500 commercial airline pilots working
in Portuguese airlines, 456 valid responses were obtained.
The inclusion criteria were: being an airline pilot on ac-
tive duty (Commanders and First Offi cers), ages between
20 and 65 yr old, and having fl own during the last 6 mo.
Questionnaire (Validation)
A pretest was used to validate the survey, which was
adapted to the Portuguese airline pilot population. This
pretest was answered by a sample of 104 pilots from
mid-January to mid-February 2012. The nine items
(questions) investigate the severity of fatigue in differ-
ent situations during the previous 2 wk. Scores range
from 1 to 7, where 1 indicates strong disagreement and
7 strong agreement. The fi nal score represents the mean
value of these nine items. The cutoff value established as
clinically signifi cant for fatigue in this scale is 4 ( 7 , 11 , 14 ).
Although the FSS had already been validated for the
Portuguese general population ( 16 , 18 ), it was decided to
validate it for the Portuguese airline pilots population.
The results of the validity and reliability analysis sug-
gested the FSS is a reliable measure to evaluate fatigue
in the study population (Mestre C; unpublished obser-
vations; 2012 ).
Final Questionnaire
The nal questionnaire also requested socio-demo-
graphic data, scales of psychological evaluation, and
questions concerning labor conditions. In order to un-
derstand the perception that pilots have in relation to
fatigue, four questions were asked: Do you feel so tired
that you think you should not be on controls? ; Have you
ever reported yourself unfi t for fl ight as a result of ac-
cumulated fatigue? ; Has it ever happened that you have
made mistakes in the cockpit as a direct consequence of
fatigue? ; and lastly How many Human Factors Confi -
dential Reports have you made on the last 6 months?
A random number was assigned to each inquiry to en-
sure that all of them were distributed by the investigating
team, thus preventing duplication and consequent fraud.
All questionnaires were put in the personal locker of
each pilot, a sample representing all Portuguese airlines.
Upon being answered, the inquiries were deposited in a
locked ballot box. The pilots were told that the inquiries
should be answered from 1 April until 15 May. Of the
1498 inquiries distributed, 456 were correctly answered,
23 were invalidated due to duplication or for being in-
correctly fi lled, and 1019 were not answered ( Fig. 1 ) .
Statistical Analysis
The minimum sample size required in the analysis to
calculate the prevalence of the study population was
based on the prevalence value achieved through the
pretest (86.5%). The equation for sample size calculation
for fi nite populations was used, based in the estimated
proportion of occurrence, for a confi dence interval of
95% and a critical value of 1.96 ( 26 , 29 ). A nal value of
approximately 180 individuals minimum was obtained.
The sample was analyzed regarding medium/short-
haul fl ights, long-haul fl ights, and total sample (which
included both types of fl ight). An exploratory factor
analysis was applied to the FSS scale. Values of Cron-
bach a 0.6 and factorial loads 0.5 were considered
acceptable, bearing in mind a preliminary exploratory
study. The comparison of fatigue levels between the two
groups was performed using the Mann-Whitney test.
A signifi cance level of 5% was considered in all the sta-
tistical analysis undertaken. Statistical analyses were
carried out with Statistica v.10 (Stat Soft. Inc., Tulsa, OK;
2011).
Ethical Considerations
The Portuguese Pilot s Association agreed to the
development of the study. In addition, the National
Commission of Data Protection was contacted and gave
their approval. The Pilots Association announced the
study to all pilots of Portuguese airlines and explained
the importance and the aim of the study. Also, the ques-
tionnaire had brief instructions explaining how to an-
swer and clarifying the objectives of the study. Informed
consent was not required because all pilots were invited
to answer the questionnaire voluntarily and anony-
mously. Furthermore, no interaction occurred between
the pilots and the researchers to jeopardize individual
privacy.
RESULTS
Table I shows the baseline characteristics of the vali-
dation test and the study population, where the similar-
ity between the two samples may be observed. For the
study population the mean age was 39.31 6 8.39 yr, 14
(3.1%) of which were women and 442 (96.9%) were men.
In the validation sample the mean age was 40.9 6 9.02 yr,
with 3 (2.9%) being women and 101 (97.1%) being men.
These numbers correspond roughly to the female/male
ratio of Portuguese airline pilots. Regarding the type
of fl ight, we obtained 127 (27.9%) valid responses for
the long haul and 314 (68.9%) for medium/short haul, a
830 Aviation, Space, and Environmental Medicine x Vol. 84, No. 8 x August 2013
FATIGUE IN AIRLINE PILOTS REIS ET AL.
proportion similar to the total number of airline pilots in
Portugal. In the validation study identical proportions
were also obtained, 80 (77.7%) for the medium/short
haul and 24 (22.3%) for the long haul. A small number of
pilots, 15 (3.3%), do both types of fl ight, although no re-
spondents in this group were part of the validation sam-
ple. With respect to the professional category, there were
59 (57.3%) Commanders and 44 (42.7%) First Offi cers
on the validation sample. However, better results were
obtained for the study sample, with a proportion of
234 (51.3%) Commanders to 222 (48.7%) First Offi cers.
Concerning working times, values obtained were very
similar for both samples, with values of duty hours in
the validation sample of 98.50 6 38.43 h and in the study
sample of 98.47 6 32.52 h; the number of fl ight hours in
the validation sample were 59.50 6 18.19 h, and in the
study population was 60.24 6 18.46 h; the number of
sectors fl own for the validation sample was 23 6 16.61
and for the study sample was 22.07 6 12.9. All values
relating to working times were calculated for 28 d.
Fig. 1. Selection of the study population.
TABLE I. BASELINE CHARACTERISTICS OF THE VALIDATION AND STUDY AIRLINE PILOT POPULATIONS.
Validation Study
Data Collection 15/01/2012 to 15/02/2012 1/04/2012 to 15/05/2012
Sample
Dimension 104 456
Age (mean 6 SD) 40.9 6 9.02 39.31 6 8.39
Sex
Male (%) 101 (97,1%) 442 (96,9%)
Female (%) 3 (2,9%) 14 (3,1%)
Professional Category
Commanders (%) 59 (57,3%) 234 (51,3%)
First Offi cers (%) 44 (42,7%) 222 (48,7%)
Type of Flight
Medium/Short Haul (%) 80 (77,7%) 314 (68,9%)
Long Haul (%) 23 (22,3%) 127 (27,9%)
Medium/Short 1 Long Haul (%)
0 (0%) 15 (3,3%)
Working Times
Duty Hours (28 d) (mean 6 SD) 98.50 6 38.43 98.47 6 32.52
Flight Hours (28 d) (mean 6 SD) 59.50 6 18.19 60.24 6 18.46
Sectors fl own (28 d) (mean 6 SD) 23.00 6 16.61 22.07 6 12.90
Aviation, Space, and Environmental Medicine x Vol. 84, No. 8 x August 2013 831
FATIGUE IN AIRLINE PILOTS REIS ET AL.
Regarding validation testing, the exploratory factor
analysis applied to the FSS for the Portuguese pilots
population presented two dimensions: mental and physi-
cal fatigue. The distinction between the two dimensions
was made by considering the content of the items as-
signed to each factor as shown in Table II . The variables
or items of the fi rst factor refer to mental or psychologi-
cal symptoms of fatigue, while the second factor variables
refer to physical symptoms of fatigue. Item 5 showed a
factorial loading greater than 0.5 in both factors regard-
ing its content of Fatigue causes frequent problems for
me, which fi t in both factors. Thus, for purposes of
score range, this item should be considered part of both
mental and physical fatigue. Regarding mental fatigue,
a factor with an eigenvalue of 4.489 was extracted, cor-
responding to 49.9% of the variance explained. Physical
fatigue showing a factor with an eigenvalue of 1.251 was
found, explaining 13.9% of the variance. The items were
distributed through the dimensions by the varimax ro-
tation method.
The reliability of the scale was assessed by measuring
internal consistency with Cronbach a , where acceptable
values of Cronbach a 0.6 were identifi ed in this pre-
liminary exploratory study. Our results showed that the
chosen scale was a reliable measure of these phenomena
in the present population, presenting a Cronbach a 5
0.856 for the total scale. Values were obtained for the
two subscales: for mental fatigue a Cronbach a 5 0.887
and for physical fatigue a Cronbach a 5 0.598, where
the subscale of physical fatigue was a nonsatisfactory
value of Cronbach a . Regarding the score for the two
subscales, it was calculated through the average of the
sum of the items considering a cutoff value of 4, as sug-
gested in the literature for the total scale ( 16 , 28 ). For the
validation study, the prevalence of clinically signifi cant
total fatigue was 86.5% and for mental fatigue was 87.5%
(FSS 4) for these pilots (Mestre C; unpublished obser-
vations; 2012 ).
Concerning the study population, the number of pi-
lots who fl ew both types of fl ights was small ( N 5 15),
and for that reason those values were only included when
analyzing the total sample, but were not considered as
a separate group. For the total sample of Portuguese
airline pilots, a percentage value of total fatigue of 89.3%
(FSS 4) was obtained. For those pilots who fl ew me-
dium/short haul, a percentage value for total fatigue of
93% was determined, and a percentage value for total
fatigue of 84.3% was obtained for those who fl ew long
haul. The comparison of the indices of total fatigue of
the two groups (medium/short haul and long haul)
showed statistically signifi cant differences between the
group of pilots who fl ew medium/short haul and the
group of pilots who fl ew long-haul fl ights (Mann-Whitney
U 5 15,772.50; P 5 0.001). Pilots who fl ew medium/short-
haul fl ights presented higher values of clinically signifi -
cant fatigue ( Fig. 2 ). Distribution analysis of the samples
( Fig. 2 ) showed that the obtained values were not in the
proximity of the cutoff point (FSS 4) but above it.
Regarding mental fatigue, a percentage value of 94.1%
(FSS 4) was obtained for the total sample of Portu-
guese airline pilots, 96.5% for medium/short-haul pilots,
and 92.1% for long-haul pilots. The comparison of the
indices of mental fatigue of the two groups once again
yielded statistically signifi cant differences between long-
haul and medium/short-haul pilots (Mann-Whitney U 5
15,882.50; P 5 0.001), with the latter presenting the high-
est values of clinically signifi cant mental fatigue ( Fig. 3 ).
The distance between the majority of the distribution of
the samples ( Fig. 3 ) and the cutoff point (FSS 4) was
even more evident for the medium/short-haul pilots.
Concerning fatigue perception, when asking pilots
Do you feel so tired that you think you should not
be on controls? , 60 (13.2%) said that never happened,
87 (19.1%) replied that happened only once, 234 (51.3%)
said a few times, and 75 (16.4%) said that happened fre-
quently. Considering the question Has it ever happened
that you have made mistakes in the cockpit as a direct
consequence of fatigue? , 417 (91.4%) pilots claimed this
had occurred. Regarding the pilots reporting fatigue
( Have you ever reported yourself unfi t for fl ight as a
result of accumulated fatigue? ), 372 (81.6%) never did,
50 (11%) reported only once, 28 (6.1%) reported a few
TABLE II. FACTOR STRUCTURE OF THE FATIGUE SEVERITY SCALE
USING PRINCIPAL COMPONENT ANALYSIS.
Statements Factor 1 Factor 2
1. My motivation is lower
when I am fatigued.
0.64
2. Exercise brings on my fatigue 0.82
3. I am easily fatigued. 0.73
4. Fatigue interferes with my
physical functioning.
0.79
5. Fatigue causes frequent problems for me. 0.58 0.52
6. My fatigue prevents sustained
physical functioning.
0.77
7. Fatigue interferes with carrying out
certain duties and responsibilities.
0.86
8. Fatigue is among my three
most disabling symptoms.
0.86
9. Fatigue interferes with my work,
family, or social life.
0.88
Fig. 2. Comparison of total fatigue for medium/short haul and long
haul pilots (* P , 0.05).
832 Aviation, Space, and Environmental Medicine x Vol. 84, No. 8 x August 2013
FATIGUE IN AIRLINE PILOTS REIS ET AL.
times, and 6 (1.3%) reported frequently. Finally, to the
question How many Human Factors Confi dential Re-
ports have you made in the last 6 months? , the great
majority had not generated any reports: 371 (81.4%) had
not and the mean value of reports made was 0.38 6 1.15
( Table III ) .
DISCUSSION
Until now, prevalence values of fatigue had not been
calculated for airline pilots in Portugal and, because of
that, it was decided to perform a validation pre-test.
During the validation for the Fatigue Severity Scale, a
total fatigue score was confi rmed as reliable. Further
analysis established two fatigue dimensions; one for
mental fatigue and the other for physical fatigue. In the
case of mental fatigue, a very robust value of Cronbach
a 5 0.887 was determined. We suspect this population is
highly affected by mental fatigue, as described in previ-
ous papers ( 9 , 24 ), where increased reaction times, short
term memory loss, impaired judgment, poorer decision-
making, and decreased visual perception have been
noted ( 9 , 23 , 24 ). All the frequency values reported for fa-
tigue were higher than expected [total fatigue 89.3%
with scores of 5.03 6 0.94 (mean 6 SD) and mental fa-
tigue 94.1% with scores of 5.62 6 0.91 (mean 6 SD)]. In
a validation study of several Swiss populations, 18% of
healthy subjects reported clinically signifi cant fatigue
with scores of 3.00 6 1.08 (mean 6 SD). Swiss patient
cohorts in this study showed higher fatigue scores: 69%
of those with multiple sclerosis scored 4.66 6 1.64, 49%
of those with ischemic stroke scored 3.90 6 1.85, and
62% with sleep-wake disorders scored 4.34 6 1.64 (all
means 6 SD) ( 28 ). All the results obtained for the pilots
population showed a fatigue frequency well above the
results obtained in these populations, which confi rmed
the complaints made by this professional class regard-
ing fatigue. One of the major problems when calculating
frequency values is the response rate of subjects, but in
this study, it was possible to achieve a large sample size
( N 5 456), which was 30.6% of the 1498 members of the
pilot group studied and higher than in other papers ( 13 ).
Another study involving airline pilots and using the
same evaluation scale was completed by the British Air-
line Pilots Association. In this study 45% of pilots re-
ported signifi cant fatigue ( 27 ). The British Airline Pilots
Association 2011 study used a cutoff point of 5, different
from the one used for the Portuguese pilot population
(FSS 4). But, even if the cutoff point for the Portuguese
population was 5, the frequency for signifi cant fatigue
would still surpass that value (59.6%).
A statistically signifi cant level of total and mental fa-
tigue was obtained between different types of fl ights,
with medium/short haul presenting the highest levels
Fig. 3. Comparison of mental fatigue for medium/short haul and long haul pilots.
TABLE III. PERCEPTION AND REPORT OF FATIGUE AMONG PORTUGUESE AIRLINE PILOTS.
Question Answer
Do you feel so tired that you think you
should not be on controls?
Never 60 (13.2%) Once 87 (19.1%) Few times 234 (51.3%) Frequently 75 (16.4%)
Has it ever happened that you have made
mistakes in the cockpit as a direct
consequence of fatigue?
Yes 417 (91.4%) No 39 (8.6%)
Have you ever reported yourself unfi t
for ight as a result of accumulated fatigue?
Never 372 (81.6%) Once 50 (11%) Few times 28 (6.1%) Frequently 6 (1.3%)
How many Human Factors Confi dential
Reports have you made in the last six months?
Min. Max.
Mean 6 SD
014
0.38 6 1.15
371 (81.4%) 1 (0.2%)
Aviation, Space, and Environmental Medicine x Vol. 84, No. 8 x August 2013 833
FATIGUE IN AIRLINE PILOTS REIS ET AL.
of fatigue compared to long haul. These data are consis-
tent with several studies over the last years, where pilots
who fl ew medium/short-haul fl ights reported higher
levels of fatigue ( 2 , 19 , 22 ), which could be a consequence
of diminished resting periods ( 15 , 22 ). Long-haul pilots
are known to have fatigue due to overnight fl ights, jet lag,
and interference with the sleep/wake cycle and body
temperature rhythm ( 5 , 21 , 23 ).
Fatigue is a subjective concept which may vary in each
individual. The evaluation instrument (FSS) is a self-
response questionnaire and our study did not attempt to
control the timing for each individual response (before,
during, or after a fl ight). This presents inherent subjec-
tivity and limitations. Nonetheless, it is a widely used
survey and it has been proven effective in the measure-
ment of subjective fatigue. When trying to understand
the perception of fatigue in Portuguese pilots, the major-
ity of pilots who responded showed good awareness
of his/her level of fatigue. However, when it came to
documenting their fatigue to the airline company (using
a Human Factors Confi dential Report), they preferred
not to report.
In this study, the prevalence of total and mental fa-
tigue among Portuguese airline pilots was established
in a solid sample of responders to our survey. Our data
support the belief that fatigue among pilots is one of the
more pressing safety issues of today s aviation industry.
Fatigue management is essential to maintain the safety
of crewmembers and the traveling public during fl ight
operations. By quantifying the level of fatigue in Portu-
guese airline pilots, we have establish crucial baseline
data and hope to create continued interest among Por-
tuguese pilots, airline companies, and aviation regula-
tors to fi nd ways to reduce the risk to fl ight safety in the
future.
ACKNOWLEDGMENTS
The authors wish to acknowledge the great importance of the
involvement of the Portuguese Airline Pilots Associations, Associação
Portuguesa de Pilotos de Linha Aérea (APPLA) and Sindicato de
Pilotos da Aviação Civil (SPAC), for their full support, especially by
highlighting the importance of this study among the pilot community.
Authors and affi liation: Cátia Reis, M.Sc., Catarina Mestre, M.Sc., and
Helena Canhão, M.D., Ph.D., Rheumatology Research Unit, Instituto
de Medicina Molecular, Faculdade de Medicina, Universidade de
Lisboa, Lisbon, Portugal.
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... These accidents or incidents resulted in 380 fatalities; 170 people were injured. Fatigue has become a significant threat to flight safety (Aljurf et al., 2018;Bandeira et al., 2018;Bendak and Rashid, 2020;Bourgeois-Bougrine, 2020;Goode, 2003;Reis et al., 2013;Williamson & Friswell, 2017). Pilots' mental health received more attention after the Germanwings crash (BEA, 2016), although estimated seventeen commercial aviation accidents and incidents, in which mental health problems or negative life events played a substantial role, caused 576 fatalities (Mulder & de Rooy, 2018). ...
... Recent research reported high levels of fatigue for 68.5% to 93% pilots (Aljurf et al., 2018;Bourgeois-Bougrine et al., 2003;Reis et al., 2013Reis et al., , 2016bVenus & grosse Holtforth, 2021b, 2021aWilliamson & Friswell, 2017). Clinically relevant sleep problems were reported by 24% to 34% pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aVenus & grosse Holtforth, 2021a). ...
... Recent research reported high levels of fatigue for 68.5% to 93% pilots (Aljurf et al., 2018;Bourgeois-Bougrine et al., 2003;Reis et al., 2013Reis et al., , 2016bVenus & grosse Holtforth, 2021b, 2021aWilliamson & Friswell, 2017). Clinically relevant sleep problems were reported by 24% to 34% pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aVenus & grosse Holtforth, 2021a). For short haul pilots, restricted rest periods, long, irregular shifts with multiple sectors (Jackson & Earl, 2006;Roach et al., 2012;Vejvoda et al., 2014;Venus & grosse Holtforth, 2021b), for long haul pilots circadian disruptions, inconsistent roster patterns on trans-meridian long haul flights and many night flights (Bendak & Rashid, 2020;Bourgeois-Bougrine et al., 2003;Gander et al., 2015;Reis et al., 2016a;Venus & grosse Holtforth, 2021b) contributed to high levels of fatigue. ...
Article
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Introduction So far, no qualitative content analysis (QCA) has analysed pilots’ experiences and perceptions regarding weaknesses of fatigue risk management (FRM), flight time limitations (FTL), rosters, fatigue-severity, sleep problems, and how they relate to pilots’ mental health and well-being. Objective This research analyses pilots’ described perceptions of stress, fatigue, aviation safety and how regulations like FTL can affect their health and well-being. Method In total, 119 international pilots described their perceptions of FTL, rosters, aviation safety, and how they relate to fatigue and health. The QCA was conducted to analyse interactions of working conditions, stressors, fatigue, sleep problems and mental health of EASA-based and Australian pilots. Results Although pilots were rostered for only 60.8% to 62.5% of the legally allowed duty and flight hours/month, 78.6% reported severe or very high fatigue, 22.8% significant depression, 12.3% significant anxiety symptoms, 10.5% reported significant depression and anxiety symptoms. Pilots uttered severe concerns about FTL, sleep restrictions associated with early starts, minimum rest, etc. Pilots also expressed distinct fears regarding more fatigue-related crashes, and how adverse working conditions, work-related and psychosocial stress could impair their health. Conclusions This QCA provided valuable insights into interactions of working conditions, fatigue, sleep restrictions, physical and mental health. Progressive health impairment due to lack of sleep and accumulated fatigue promote burnout, mental and physical health problems, which not only threaten flight safety, but also sustainability of aviation.
... These accidents or incidents resulted in 380 fatalities; 170 people were injured. Fatigue has become a significant threat to flight safety (Aljurf et al., 2018;Bandeira et al., 2018;Bendak and Rashid, 2020;Bourgeois-Bougrine, 2020;Goode, 2003;Reis et al., 2013;Williamson & Friswell, 2017). Pilots' mental health received more attention after the Germanwings crash (BEA, 2016), although estimated seventeen commercial aviation accidents and incidents, in which mental health problems or negative life events played a substantial role, caused 576 fatalities (Mulder & de Rooy, 2018). ...
... Recent research reported high levels of fatigue for 68.5% to 93% pilots (Aljurf et al., 2018;Bourgeois-Bougrine et al., 2003;Reis et al., 2013Reis et al., , 2016bVenus & grosse Holtforth, 2021b, 2021aWilliamson & Friswell, 2017). Clinically relevant sleep problems were reported by 24% to 34% pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aVenus & grosse Holtforth, 2021a). ...
... Recent research reported high levels of fatigue for 68.5% to 93% pilots (Aljurf et al., 2018;Bourgeois-Bougrine et al., 2003;Reis et al., 2013Reis et al., , 2016bVenus & grosse Holtforth, 2021b, 2021aWilliamson & Friswell, 2017). Clinically relevant sleep problems were reported by 24% to 34% pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aVenus & grosse Holtforth, 2021a). For short haul pilots, restricted rest periods, long, irregular shifts with multiple sectors (Jackson & Earl, 2006;Roach et al., 2012;Vejvoda et al., 2014;Venus & grosse Holtforth, 2021b), for long haul pilots circadian disruptions, inconsistent roster patterns on trans-meridian long haul flights and many night flights (Bendak & Rashid, 2020;Bourgeois-Bougrine et al., 2003;Gander et al., 2015;Reis et al., 2016a;Venus & grosse Holtforth, 2021b) contributed to high levels of fatigue. ...
Article
Introduction So far, no qualitative content analysis (QCA) has analysed pilots’ experiences and perceptions regarding weaknesses of fatigue risk management (FRM), flight time limitations (FTL), rosters, fatigue-severity, sleep problems, and how they relate to pilots’ mental health and well-being. Objective This research analyses pilots’ described perceptions of stress, fatigue, aviation safety and how regulations like FTL can affect their health and well-being. Method In total, 119 international pilots described their perceptions of FTL, rosters, aviation safety, and how they relate to fatigue and health. The QCA was conducted to analyse interactions of working conditions, stressors, fatigue, sleep problems and mental health of EASA-based and Australian pilots. Results Although pilots were rostered for only 60.8% to 62.5% of the legally allowed duty and flight hours/month, 78.6% reported severe or very high fatigue, 22.8% significant depression, 12.3% significant anxiety symptoms, 10.5% reported significant depression and anxiety symptoms. Pilots uttered severe concerns about FTL, sleep restrictions associated with early starts, minimum rest, etc. Pilots also expressed distinct fears regarding more fatigue-related crashes, and how adverse working conditions, work-related and psychosocial stress could impair their health. Conclusions This QCA provided valuable insights into interactions of working conditions, fatigue, sleep restrictions, physical and mental health. Progressive health impairment due to lack of sleep and accumulated fatigue promote burnout, mental and physical health problems, which not only threaten flight safety, but also sustainability of aviation.
... Thirty-one studies included the evaluation of behavioral cardiometabolic risk factors. Alcohol intake was investigated in 10 samples of airline pilots [6,24,27,33,36,38,39,46,47,57,60,61]; one study utilized a validated questionnaire [36], and five studies [27,33,36,38,39] (n = 2538) ascertained "regular alcohol intake" on the basis of a participant self-recall question, producing a pooled prevalence of 52% (51.3-53.1). Twelve studies [6,26,27,29,32,33,36,37,39,49,57,60] (n = 19,116) reported smoking prevalence, yet no studies evaluated quantity or frequency of smoking. ...
... Furthermore, other studies reported that <6 h of sleep per night was associated with obesity [41] and poor sleep quality [42] within participants. The prevalence of excessive sleepiness assessed by the Epworth Sleepiness Scale (score ≥10) was reported by five studies [19,20,39,42,46], exhibiting a pooled prevalence of 44.5% (44.1-44.8%). Among four studies reporting high obstructive sleep apnea (OSA) risk ascertained from the Berlin Questionnaire, the prevalence was 5% [19], 20% [39], 21% [42], and 29% [20], providing a pooled mean of 21.4% (21.3-21.5%). ...
... Sixteen studies included an evaluation of psychological cardiometabolic risk factors. Among 10 studies investigating the prevalence of psychological fatigue, four studies (n = 2987) utilized the Fatigue Severity Scale (FSS), two of which reported a psychological fatigue prevalence (FSS ≥ 4 mean score) of 77% [54] and 89% [46,47]. Another two studies reported the severe psychological fatigue prevalence (FSS ≥ 36 total score) as 33% [19] and 68% [20]. ...
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Background: The occupational demands of professional airline pilots such as shift work, work schedule irregularities, sleep disruption, fatigue, physical inactivity, and psychological stress may promote adverse outcomes to cardiometabolic health. This review investigates the prevalence of cardiometabolic health risk factors for airline pilots. Methods: An electronic search was conducted utilizing PubMed, MEDLINE (via OvidSP), CINAHL, PsycINFO, SPORTDiscus, CENTRAL, and Web of Science for publications between 1990 and February 2022. The methodological quality of included studies was assessed using two quality assessment tools for cross-sectional and clinical trial studies. The prevalence of physiological, behavioral, and psychological risk factors was reported using descriptive analysis. Results: A total of 48 studies derived from 20 different countries, reviewing a total pooled sample of 36,958 airline pilots. Compared with general population estimates, pilots had a similar prevalence for health risk factors, yet higher sleep duration, lower smoking and obesity rates, less physical activity, and a higher overall rate of body mass index >25. Conclusions: The research reported substantial prevalence >50% for overweight and obesity, insufficient physical activity, elevated fatigue, and regular alcohol intake among pilots. However, the heterogeneity in methodology and the lack of quality and quantity in the current literature limit the strength of conclusions that can be established. Enhanced monitoring and future research are essential to inform aviation health practices and policies (Systematic Review Registration: PROSPERO CRD42022308287).
... Several authors argue that fatigue prevention through FTL and Fatigue Risk Management (FRM) could probably not avoid high fatigue levels in active pilots (e.g., Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aReis et al., , 2016b. Although high levels of pilots' fatigue represent a significant safety risk during flight operations (Aljurf et al., 2018;Coombes et al., 2020;Goode, 2003;Reis et al., 2013Reis et al., , 2016aWilliamson & Friswell, 2017), severe fatigue (FSS ≥4) was reported by 68.3% up to 93% of the investigated pilots (Aljurf et al., 2018;Reis et al., 2016b;Venus & grosse Holtforth, 2021a, 2021b. ...
... Several authors argue that fatigue prevention through FTL and Fatigue Risk Management (FRM) could probably not avoid high fatigue levels in active pilots (e.g., Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aReis et al., , 2016b. Although high levels of pilots' fatigue represent a significant safety risk during flight operations (Aljurf et al., 2018;Coombes et al., 2020;Goode, 2003;Reis et al., 2013Reis et al., , 2016aWilliamson & Friswell, 2017), severe fatigue (FSS ≥4) was reported by 68.3% up to 93% of the investigated pilots (Aljurf et al., 2018;Reis et al., 2016b;Venus & grosse Holtforth, 2021a, 2021b. In comparison, smaller proportions of the general or healthy population reported severe fatigue in FSS validation studies (Krupp et al., 1989;Lerdal et al., 2005;Valko et al., 2008). ...
... Over the past few years, several studies have reported high levels of pilot fatigue (Aljurf et al., 2018;Bourgeois-Bougrine et al., 2003;Reis et al., 2013Reis et al., , 2016aVenus & grosse Holtforth, 2021a, 2021b, 2022. Deteriorating working conditions of airline pilots were associated with more stress and impaired wellbeing (Cahill et al., 2021;Cullen et al., 2020;Sloan & Cooper, 1986;Widyahening, 2007). ...
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Objective This study Investigates more dimensions than previous studies simultaneously: pilots’ duty rosters, stress, sleep difficulties, fatigue levels, wellbeing, symptoms of depression, anxiety, and common mental disorders (CMD), and how they are interrelated. Background Several scientific studies have confirmed that fatigue can pose a significant risk to flight safety. Other studies reported positive depression screening results for more pilots, compared with the general population. Method A cross-sectional online survey was completed by 406 international pilots, who reported their duty rosters of the last two months. Pilots also self-assessed their stress-levels, sleep problems, fatigue, wellbeing, and mental health. Results Although pilots were on average rostered for only 60% of maximum legal duty and flight hours, three out of four pilots (76%) reported severe or high fatigue. Every fourth pilot reported considerable sleep difficulties (24%). 18.7% pilots reported positive depression screening results, 8.5% positive anxiety screenings, 7.2% reported significant symptoms of depression and anxiety. Highly significant to high correlations between stress, sleep problems, fatigue, symptoms of depression, anxiety, CMD and well-being were found. Conclusions Chronic stress appears to be linked to psychophysiological wear and tear, and was associated with higher levels of fatigue, more sleep disturbances and more impaired mental health. Future research should not only consider fatigue as an immediate threat to aviation safety, but also as a significant threat to pilots’ safety-relevant fitness to fly.
... In this study, we are referring to professional or airline pilots as opposed to private pilots. In accordance with Shahid et al. (2010) we differentiate between alertness/sleepiness and more accumulated fatigue, similar to previous studies (Aljurf et al., 2018;Cabon et al., 2012;Reis et al., 2013;Reis et al., 2016a;Shahid et al., 2010). ...
... Despite various measures to prevent fatigue, several studies have consistently reported high levels of fatigue in active commercial pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aReis et al., , 2016b. Severe fatigue was reported by 68.3% to 93% pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aReis et al., , 2016bVenus and grosse Holtforth, 2021a), although pilots' high on-duty sleepiness and fatigue represents an operational safety risk (Aljurf et al., 2018;Coombes et al., 2020;Goode, 2003;Reis et al., 2013Reis et al., , 2016aWilliamson & Friswell, 2017). ...
... Despite various measures to prevent fatigue, several studies have consistently reported high levels of fatigue in active commercial pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aReis et al., , 2016b. Severe fatigue was reported by 68.3% to 93% pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aReis et al., , 2016bVenus and grosse Holtforth, 2021a), although pilots' high on-duty sleepiness and fatigue represents an operational safety risk (Aljurf et al., 2018;Coombes et al., 2020;Goode, 2003;Reis et al., 2013Reis et al., , 2016aWilliamson & Friswell, 2017). Validation studies of the Fatigue Severity Scale (Krupp et al., 1989) showed less fatigue for healthy individuals (non-pilots) and some patient groups (Lerdal et al., 2005;Valko et al., 2008). ...
Article
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Introduction: Recent research has reported widespread high levels of fatigue among pilots. Pilot fatigue can affect their performance and has become a threat to flight safety. Objective: This study examines whether different flight time limitations (FTL) and rosters of EASA-based and Australian pilots were associated with different levels of stress, sleep difficulties, fatigue levels, symptoms of depression or anxiety and wellbeing. Method: 192 EASA-based and 180 Australian pilots completed a cross-sectional online survey, which asked for their schedules, stress, sleep problems, fatigue, wellbeing, and symptoms of depression and anxiety. These variables were compared for the groups of EASA-based and Australian pilots. Findings: Although EASA based and Australian pilots were scheduled for only 57–62% of maximum duty and flight hours, 71.8% EASA-based vs. 77% Australian pilots reported severe or high fatigue. Significant depression symptoms were reported by 17.2% Australian and 18% EASA-based pilots, 7% pilots reported significant symptoms of depression and anxiety. Australian pilots reported more demanding rosters, significantly more sleep problems and significantly lower wellbeing. Conclusions: Present regulations and FTL likely could not prevent high fatigue levels among EASA based and Australian pilots. Both groups were equally fatigued, although Australian pilots reported more demanding rosters. Pilots of both groups reported the same levels of stress, depression, and anxiety symptoms, while Australian pilots’ sleep and wellbeing were significantly more impaired. These results suggest that fatigue should not be regarded as an isolated problem for flight-safety. Fatigue is closely related to pilots’ physical and mental health, which may be at risk in the long run.
... Sleep problems and fatigue are not isolated problems, but closely related to stress (Ekstedt et al., 2006;Kalmbach et al., 2020;Lundberg & Frankenhaeuser, 1999;Omholt et al., 2017;Sapolsky, 2004;Sloan & Cooper, 1986;Venus, 2020) and burnout (Demerouti et al., 2019;Fanjoy et al., 2010). Despite fatigue prevention measures like fatigue risk management (FRM) and FTL, several studies reported high levels of fatigue among active professional pilots (Aljurf et al., 2018;Reis et al., 2013Reis et al., , 2016aReis et al., , 2016b. These studies measured fatigue with the Fatigue Severity Scale (FSS, Krupp et al., 1989). ...
... These studies measured fatigue with the Fatigue Severity Scale (FSS, Krupp et al., 1989). Severe fatigue (FSS≥4) was reported by 68.5% (Aljurf et al., 2018) up to 93% pilots (Reis et al., 2013(Reis et al., , 2016a(Reis et al., , 2016bVenus & grosse Holtforth, 2021), although pilots' high levels of fatigue are associated with high operational safety risks (Aljurf et al., 2018;Coombes et al., 2020;Goode, 2003;Reis et al., 2013Reis et al., , 2016aWilliamson & Friswell, 2017). FSS Validation studies reported lower fatigue levels in the general or healthy population (Lerdal et al., 2005;Valko et al., 2008). ...
... These studies measured fatigue with the Fatigue Severity Scale (FSS, Krupp et al., 1989). Severe fatigue (FSS≥4) was reported by 68.5% (Aljurf et al., 2018) up to 93% pilots (Reis et al., 2013(Reis et al., , 2016a(Reis et al., , 2016bVenus & grosse Holtforth, 2021), although pilots' high levels of fatigue are associated with high operational safety risks (Aljurf et al., 2018;Coombes et al., 2020;Goode, 2003;Reis et al., 2013Reis et al., , 2016aWilliamson & Friswell, 2017). FSS Validation studies reported lower fatigue levels in the general or healthy population (Lerdal et al., 2005;Valko et al., 2008). ...
Article
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Objective While previous research focused on pilots’ fatigue, rosters, potential performance-impairment and aviation-safety, this research investigates, how pilots’ work-related and psychosocial stress and rosters can affect their sleep and fatigue. Method A cross-sectional online survey was completed by 192 pilots flying for European operators, 180 Australian pilots and 34 pilots from UAE, Turkey and Asia Pacific. Pilots reported their actual duty- and flight-hours, flown sectors, standby, rest, vacation days, number of early starts, night-flights and sports-hours for the last two months. Schedule-related data, way to work, age, flight-hours on the present type of aircraft, subjective job-security and psychosocial stress were used as independent variables to investigate, which significantly predict sleep problems (JSS) and fatigue (FSS). Results 76% of the active pilots reported significant fatigue (FSS≥4), 33.4% high fatigue (FSS≥5), although pilots were rostered for only 56.25% to 61.32% of the legally allowed duty and flight hours/month. Considerable sleep problems in ≥8 nights/month were reported by 24.2% pilots. Sleep problems were strongly associated with sleep restrictions and fatigue risks experienced on flight duty. More sleep problems were predicted by more stress and fatigue risks on flight duty. Higher fatigue-severity was predicted by more sleep problems, more stress, more fatigue risks experienced on flight duty, less physical exercise and shorter ways to work. Conclusions Our findings suggest that present flight-time-limitations likely cannot prevent fatigue and potentially foster sleep-problems. In line with work-psychology and stress-research, psychosocial stress plays an important role for pilots’ sleep problems and fatigue.
... This was confirmed by a survey of pilots, with >80% reporting that fatigue affected their flight performance (Gregory et al., 2010). In two other studies 67 and 90% of pilots reported ever having made mistakes due to fatigue (Reis et al., 2013;Aljurf et al., 2018). ...
... More recent studies, however, found that the prevalence of fatigue was significantly higher in SH than in LH operations (93% vs. 84.3%), with a 2.945 added risk of fatigue in SH pilots (Reis et al., 2013(Reis et al., , 2016. This shift in prevalence may have been due to developments in air travel. ...
Article
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Fatigue poses an important safety risk to civil and military aviation. In addition to decreasing performance in-flight (chronic) fatigue has negative long-term health effects. Possible causes of fatigue include sleep loss, extended time awake, circadian phase irregularities and work load. Despite regulations limiting flight time and enabling optimal rostering, fatigue cannot be prevented completely. Especially in military operations, where limits may be extended due to operational necessities, it is impossible to rely solely on regulations to prevent fatigue. Fatigue management, consisting of preventive strategies and operational countermeasures, such as pre-flight naps and pharmaceuticals that either promote adequate sleep (hypnotics or chronobiotics) or enhance performance (stimulants), may be required to mitigate fatigue in challenging (military) aviation operations. This review describes the pathophysiology, epidemiology and effects of fatigue and its impact on aviation, as well as several aspects of fatigue management and recommendations for future research in this field.
... Since this study was composed only by Portuguese aircraft maintenance workers, it would be important to test the invariance between countries for other Portuguese-speaking populations (e.g., Brazil and Angola). To test OLBI's psychometric properties for other groups from the aviation field, like airline pilots, would be also highly relevant since they are also critical workers of the aviation industry, presenting reported high levels of fatigue and sleep problems (Reis et al., 2013(Reis et al., , 2016, although with higher control of work and rest periods, as well as redundancy protocols (EASA, 2018). ...
Article
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From its initial conceptualization as emotional exhaustion, cynicism, and reduced personal efficacy for the help professions, burnout has received increasing attention in modern times, especially after the 2019 WHO's inclusion of this syndrome in the ICD-11 list. Burnout can be measured using several psychometric instruments that range in dimensionality, number of items, copyrighted, and free use formats. Here, we report the psychometric properties of data gathered with the Oldenburg Burnout Inventory (OLBI) in a sample of Portuguese Aircraft maintenance technicians. As far as we know, this is the first study addressing the burnout syndrome in this occupational group. Data gathered with the OLBI displayed good evidence of validity related to internal structure, to other variables, with good evidence of reliability. We showed that burnout significantly correlated with mental and physical fatigue emphasizing the vital critical role that these variables play with safety in the aviation industry.
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Background: Research in sport, military, and aerospace populations has shown that mental fatigue may impair cognitive performance. The effect of nutritional interventions that may mitigate such negative effects has been investigated. This systematic review and meta-analysis aimed to quantify the effects of nutritional interventions on cognitive domains often measured in mental fatigue research. Methods: A systematic search for articles was conducted using key terms relevant to mental fatigue in sport, military, and aerospace populations. Two reviewers screened 11,495 abstracts and 125 full texts. A meta-analysis was conducted whereby effect sizes were calculated using subgroups for nutritional intervention and cognitive domains. Results: Fourteen studies were included in the meta-analysis. The consumption of energy drinks was found to have a small positive effect on reaction time, whilst the use of beta-alanine, carbohydrate, and caffeine had no effect. Carbohydrate and caffeine use had no effect on accuracy. Conclusions: The results of this meta-analysis suggest that consuming energy drinks may improve reaction time. The lack of effect observed for other nutritional interventions is likely due to differences in the type, timing, dosage, and form of administration. More rigorous randomized controlled trials related to the effect of nutrition interventions before, during, and after induced mental fatigue are required.
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Background Fatigue is highly prevalent and has a negative impact on quality of life and performance in a variety of disorders. The 9-item Fatigue Severity Scale (FSS) is one of the most commonly used self-report questionnaires to measure fatigue, but has only been validated in small sample-sized studies and in single disorders. Objective To validate the FSS in healthy subjects and different disorders known to be commonly associated with fatigue. Material and Methods The FSS was administered to 454 healthy subjects, 188 patients with multiple sclerosis (MS), 235 patients with recent ischemic stroke, and 429 patients with sleep-wake disorders including narcolepsy with cataplexy (n = 22), restless legs syndrome (RLS) (n = 79), sleep apnea (n = 108), insomnia (n = 62), parasomnia (n = 25), excessive daytime sleepiness/hypersomnia of other origin (n = 84), and other sleep-wake disorders (n = 49). Results FSS scores were 4.66 ± 1.64 (mean ± SD) in patients with MS, 3.90 ± 1.85 in patients after ischemic stroke, and 4.34 ± 1.64 in patients with sleep-wake disorders. Compared to patients, values were significantly lower in healthy subjects (3.00 ± 1.08, P < 0.01). Scores did not correlate with gender, age, or education. Item analysis showed an excellent internal consistency and reliability (Cronbach α = 0.93). Test-retest variability was assessed in 104 healthy subjects, showing stable values over time (2.94 ± 0.90 vs. 2.90 ± 0.74; P = 0.27). Conclusions This first validation of a fatigue scale in a large sample size demonstrates that the FSS is a simple and reliable instrument to assess and quantify fatigue for clinical and research purposes.
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The main purpose of this study was the adaptation of the Fatigue Severity Scale (Krupp et al., 1989), which was designed to assess the perception of fatigue levels in patients with Systemic Lupus Erythematosus (SLE). Using a sample of 104 patients with SLE, the results showed that the Fatigue Severity Scale had a fidelity coefficient of .96, which indicates a high internal consistency of the items, like the original version (.88). The factor analysis showed the items, in the adapted version, to be organized in one factor only, as it happens in the original version. Thus, the Fatigue Severity Scale has good psychometric qualities that allow its use as an assessment tool in the evaluation the perception of fatigue in the Portuguese population of patients with Systemic Lupus Erythematosus. In terms of construct validity results showed, in patients with SLE, higher perceived fatigue to be associated with low quality of life in every domain (physical, psychological, social relationships and environment) and more depressive and anxiety symptoms.
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In this study we describe our experience of voluntary fatigue reporting among pilots and cabin crew. This was a prospective study to determine the crude incidence rate and primary cause of fatigue report form submission among cabin crew and pilots within one airline. All crew duties had already undergone scrutiny at the 'roster build' stage to ensure compliance with fatigue control measures. Reports were investigated by the airline's medical officer to determine the primary cause of fatigue and then allocated to one of five categories. The frequency and proportion of reports within each category was determined. The crude incidence rate of fatigue report submission was 103 and 68 cases per 1000 persons per year for pilots and cabin crew, respectively. The primary cause for 27% of reports was attributed to the rostered duty pattern. Of the reports, 24% were primarily caused by roster disruption, 17% by problems with layover accommodation or transport, 23% by a domestic issue, and 9% had no obvious cause or were deemed invalid. A subanalysis of the 'domestic' category revealed that half had a primary cause attributable to commuting to or from the workplace. The number and trend of reports received per month can be used to detect otherwise unknown fatigue hazards and identify where improvements can be made. Fatigue reports allow individual crewmembers to give vital feedback on 'whole-of-life' fatigue risks, both inside and outside the workplace.
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The Fatigue Severity Scale (FSS) is a widely used instrument to measure the impact of fatigue on specific types of functioning. This study aims to translate and test the reliability and validity of the Portuguese version of the FSS. The questionnaire was administered to a worker sample of 424 nurses. Reliability analysis showed satisfactory results (Cronbach's alpha coefficient = .87). The test-retest reliability was .85. The principal component analysis showed that the FSS was a measure with a one-factor structure. The construct validity of the total FSS score was assessed by correlation with Maslach Burnout Inventory (MBI) score, Depression Anxiety Stress Scale (DASS) score, and Visual Analogue Scale (VAS) score. Each of the corresponding correlation coefficients among the total FSS score and MBI score, DASS score, and perceived fatigue score (VAS) were .55 (p < .01), .62 (p < .01), and .68 (p < .01), respectively, which shows sufficient construct validity. To measure the discriminant validity of FSS, we examined the differences in scores between groups in terms of the number of hours of sleep and overtime. The less nurses slept and the longer they worked, the higher their total FSS score became. This preliminary validation study of the Portuguese version of FSS proved that it is an acceptable, reliable, and valid measure of fatigue in the working population.
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